Quérat B, Hardy A, Fontaine Y A
Laboratoire de Physiologie Générale et Comparée du MNHN, Unité d'Endocrinologie Comparée du CNRS, URA 90, Paris, France.
J Mol Endocrinol. 1991 Aug;7(1):81-6. doi: 10.1677/jme.0.0070081.
The gonadotrophic function of the European eel (Anguilla anguilla L.) at the silver stage is very weak: gonadotrophin-releasing hormone (GnRH) secretion is deficient and, moreover, dopamine inhibition overrides GnRH action. At the silver stage, oestradiol stimulates the biosynthesis of the type-II gonadotrophin (GTH-II). To study the molecular mechanism of this activation further, we examined the effect of testosterone and oestradiol administration on pituitary levels of mRNA encoding GTH-II alpha and beta subunits. Corresponding eel cDNA probes and Northern blot analysis were used. After 2 weeks, testosterone and oestradiol implantation resulted in a strong increase in mRNA encoding the GTH-II beta subunit (7-fold and 25-fold, respectively) and in a slight, but non-significant, rise in the a subunit mRNA level (1.8-fold and 1.5-fold, respectively). Co-implantation of these two steroids suggested a potentiation of their effects on the beta subunit (104-fold) while an additive effect was indicated on the alpha mRNA level (2.9-fold). Effects were detectable within 4 days and were maximal 4 weeks after implantation. These results indicate that in the European eel at the silver stage, gonadal steroids stimulate differentially the expression of GTH-II subunit genes at a pretranslational level.
欧洲鳗鲡（Anguilla anguilla L.）在银期的促性腺功能非常弱：促性腺激素释放激素（GnRH）分泌不足，而且多巴胺抑制作用超过了GnRH的作用。在银期，雌二醇刺激II型促性腺激素（GTH-II）的生物合成。为了进一步研究这种激活的分子机制，我们检测了睾酮和雌二醇给药对垂体中编码GTH-IIα和β亚基的mRNA水平的影响。使用了相应的鳗鲡cDNA探针和Northern印迹分析。2周后，睾酮和雌二醇植入导致编码GTH-IIβ亚基的mRNA大幅增加（分别为7倍和25倍），而α亚基mRNA水平略有升高但不显著（分别为1.8倍和1.5倍）。这两种类固醇的共同植入表明它们对β亚基的作用有增强（104倍），而对α亚基mRNA水平有相加作用（2.9倍）。在植入后4天内可检测到效应，植入后4周效应最大。这些结果表明，在银期的欧洲鳗鲡中，性腺类固醇在翻译前水平上对GTH-II亚基基因的表达有不同的刺激作用。
